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Current Concepts

Current Concepts in the Rehabilitation ofthe Overhead Throwing Athlete

Kevin E. Wilk,*† PT, Keith Meister,‡ MD, and James R. Andrews,§� MD

From *HealthSouth Rehabilitation Corporation and American Sports Medicine Institute,Birmingham, Alabama, �Tampa Bay Devil Rays Baseball Team, Tampa Bay, Florida,

‡Department of Orthopaedics, Division of Sports Medicine, University of Florida, Gainesville,Florida, and §Alabama Sports Medicine and Orthopaedic Center, Birmingham, Alabama

ABSTRACT

The overhead throwing motion is an extremely skillfuland intricate movement that is very stressful on theshoulder joint complex. The overhead throwing athleteplaces extraordinary demands on this complex. Exces-sively high stresses are applied to the shoulder jointbecause of the tremendous forces generated by thethrower. The thrower’s shoulder must be lax enough toallow excessive external rotation, but stable enough toprevent symptomatic humeral head subluxations, thusrequiring a delicate balance between mobility and func-tional stability. We refer to this as the “thrower’s para-dox.” This balance is frequently compromised, whichleads to injury. Numerous types of injuries may occurto the surrounding tissues during overhead throwing.Frequently, injuries can be successfully treated with awell-structured and carefully implemented nonopera-tive rehabilitation program. The key to successful non-operative treatment is a thorough clinical examinationand accurate diagnosis. Athletes often exhibit numer-ous adaptive changes that develop from the repetitivemicrotraumatic stresses observed during overheadthrowing. Treatment should focus on the restoration ofthese adaptations during the rehabilitation program. Inthis article, the typical musculoskeletal profile of theoverhead thrower and various rehabilitation programsfor specific injuries are discussed. Rehabilitation fol-lows a structured, multiphase approach with emphasison controlling inflammation, restoring muscle balance,improving soft tissue flexibility, enhancing propriocep-

tion and neuromuscular control, and efficiently return-ing the athlete to competitive throwing.

The repetitive microtraumatic stresses placed on the ath-lete’s shoulder joint complex during the throwing motionchallenge the physiologic limits of the surrounding tis-sues. Frequently, alterations in throwing mechanics, mus-cle fatigue, muscle weakness or imbalance, and excessivecapsular laxity may lead to tissue breakdown and injury.These injuries frequently involve the glenohumeral cap-sule, glenoid labrum, and the rotator cuff musculature.

It has been our experience that most injuries to thethrower’s shoulder can be effectively treated with a propernonoperative rehabilitation program. Generally, the reha-bilitation program consists of activity modification, flexi-bility exercises, strengthening exercises, and a gradualreturn to throwing activities. In part one of his “CurrentConcepts” series, Meister 64 described a four-group classi-fication system to categorize shoulder injuries in the over-head throwing athlete. We will discuss the rehabilitationprogram for each of the classifications. Bison and An-drews10 have also offered a classification system for inju-ries to the thrower’s shoulder. Each of these abnormalitiesdevelops because of unique etiologic factors. On the basisof these etiologic factors and the clinical examination, aproper rehabilitation program can be developed for eachcategory. The key to effective treatment is a thoroughclinical examination and appropriate differential diagno-sis. In this article, we will discuss a typical nonoperativerehabilitation program for various shoulder injuries thathave been discussed in the previous two articles.

REHABILITATION OVERVIEW

Before the specifics of the rehabilitation program can bediscussed, a thorough understanding of the clinical exam-

† Address correspondence and reprint requests to Kevin E. Wilk, PT,HealthSouth Rehabilitation Corporation, 1201 11th Avenue South, Suite 100,Birmingham, AL 35202.

No author or related institution has received financial benefit from researchin this study.

0363-5465/102/3030-0136$02.00/0THE AMERICAN JOURNAL OF SPORTS MEDICINE, Vol. 30, No. 1© 2002 American Orthopaedic Society for Sports Medicine

136

ination of the shoulder joint complex must be established.The evaluation of the thrower’s shoulder has been dis-cussed in part two of the series by Meister.63 The physi-cian must evaluate the thrower to establish a differentialdiagnosis, then the physical therapist or athlete trainermust evaluate the thrower to establish a list of physicallimitations or problems that may be contributing to orresulting from the disorder. The rehabilitation specialistmust evaluate range of motion, muscle strength, laxity,and proprioception. In addition, the rehabilitation special-ist should address the athlete’s throwing program, exer-cise schedule, and throwing mechanics. Once these areashave been assessed, a comprehensive rehabilitation pro-gram can be established. Furthermore, during the evalu-ation process, the clinician must have an understanding ofwhat is considered to be the “normal” or acceptable phys-iologic characteristics for the overhead throwingpopulation.

The purpose of the following sections is to convey to thereader the typical physical characteristics of the overheadthrowing athlete. Specific range of motion, strength, lax-ity, and proprioceptive characteristics exhibited in throw-ing athletes will be discussed. The clinician must possessa complete understanding of what is typical for thisunique athletic population so that abnormalities or differ-ences can be appropriately identified and addressed.

Range of Motion

Most throwers exhibit an obvious motion disparitywhereby external rotation is excessive and internal rota-tion is limited at 90° of abduction.8,15,47,92 Several inves-tigators have documented that pitchers exhibit greaterexternal rotation of the shoulder than do position play-ers.8,47,93 Brown et al.15 reported that professional pitch-ers exhibited 141° � 15° of shoulder external rotationmeasured at 90° of abduction. This was approximately 9°more than the nonthrowing shoulder, and approximately9° more than the throwing shoulder of position playersmeasured in 90° of abduction. Recently, Bigliani et al.8

examined the range of motion of 148 professional players.The investigators reported that the pitchers’ external ro-tation at 90° of abduction averaged 118° (range, 95° to145°) in the dominant shoulder, whereas the position play-ers’ dominant shoulder averaged 108° (range, 80° to 105°).

In an ongoing study of professional baseball players,Wilk and Arrigo (unpublished data, 2000) assessed therange of shoulder motion of 372 professional baseball play-ers. We have noted that pitchers exhibit an average of129.9° � 10° of external rotation and 62.6° � 9° of internalrotation when passively assessed at 90° of abduction. Inpitchers, the external rotation is approximately 7° greaterin the throwing shoulder when compared with the non-throwing shoulder, while internal rotation is 7° greater inthe nonthrowing shoulder. In addition, the total motion(external rotation and internal rotation added together) inthe throwing shoulder is equal (within 5°) when comparedwith the nonthrowing shoulder. This was consistent in all372 baseball players. We refer to this as the “total motionconcept” (Fig. 1). We have also noted that pitchers exhibit

the greatest total arc of motion; that is, external andinternal rotation at 90° of abduction, followed closely bycatchers, then outfielders, and finally infielders. Further-more, when comparing left-handed with right-handedpitchers, the left-handed throwers exhibit approximately7° more external rotation and 12° more total motion whencompared with right-handed throwers. These findingswere statistically significant (P � 0.01).

Laxity

Most throwers exhibit significant laxity of the glenohu-meral joint, which permits excessive range of motion. Thehypermobility of the thrower’s shoulder has been referredto as “thrower’s laxity.”92 The laxity of the anterior andinferior glenohumeral joint capsule may be appreciated bythe clinician during the stability assessment of the over-head thrower’s shoulder joint. Some clinicians have re-ported that the excessive laxity exhibited by the thrower isthe result of repetitive throwing and they have referred tothis as “acquired laxity” (J. R. Andrews, unpublished data,1996), while others have documented that the overheadthrower exhibits congenital laxity.8

Bigliani et al.8 examined laxity in 72 professional base-ball pitchers and 76 position players. The investigatorsnoted a high degree of inferior glenohumeral joint laxity,with 61% of pitchers and 47% of position players exhibit-ing a positive sulcus sign in the throwing shoulder. Addi-tionally, in the players who also exhibited a positive sul-cus sign in the dominant shoulder, 89% of the pitchers and100% of the position players exhibited a positive sulcussign in the nondominant shoulder. Thus, it would appearthat some baseball players exhibit inherent or congenitallaxity, with superimposed acquired laxity, as a result ofadaptive changes from throwing.

Fig. 1. The total motion concept: ER � IR � total motion.ER, external rotation; IR, internal rotation.

Vol. 30, No. 1, 2002 Rehabilitation of the Overhead Throwing Athlete 137

Muscle Strength

Several investigators have examined muscle strength pa-rameters in the overhead throwing athlete with varyingresults and conclusions.1,7,15,20,22,39,89,91 Wilk et al.89,91

performed isokinetic testing on professional baseball play-ers as part of their physical examinations during springtraining. The investigators demonstrated that the exter-nal rotation strength of the pitcher’s throwing shoulder issignificantly weaker (P � 0.05) than the nonthrowingshoulder, by 6%. Conversely, internal rotation strength ofthe throwing shoulder was significantly stronger (P �0.05), by 3%, compared with the nonthrowing shoulder. Inaddition, adduction strength of the throwing shoulder isalso significantly stronger than in the nonthrowing shoul-der, by approximately 9% to 10%. We believe that animportant isokinetic value is the unilateral muscle ratio,which describes the antagonist/agonist muscle strengthratio. A proper balance between agonist and antagonistmuscle groups is thought to provide dynamic stabilizationto the shoulder joint. To provide proper muscle balance,

the external rotator muscles should be at least 65% thestrength of the internal rotator muscles.94 Optimally, theexternal-to-internal rotator muscles strength ratio shouldbe 66% to 75%.91,94,96 This provides proper muscle bal-ance. Table 1 illustrates the expected muscle strengthvalues of professional baseball players.

Magnusson et al.60 used a hand-held dynamometer tostudy the isometric muscle strength of professional pitch-ers and compared it with strength of a control group ofnonthrowing, nonathletic persons. In pitchers, the su-praspinatus muscle was significantly weaker on thethrowing side compared with the nonthrowing side; thiswas tested by performing an isometric manual muscle testof the empty can maneuver. Additionally, pitchers wereweaker than the control group of nonbaseball players forshoulder abduction, external rotation, internal rotation,and muscle strength of the supraspinatus muscle.

The scapular muscles play a vital role during the over-head throwing motion.26 Proper scapular movement andstability are imperative for asymptomatic shoulder func-tion.48,49 These muscles work in a synchronized fashionand act as force couples about the scapula, providing bothmovement and stabilization. Wilk et al.97 documented theisometric scapular muscle strength values of professionalbaseball players. The results indicated that pitchers andcatchers exhibited a significantly different strength in-crease of the protractor and elevator muscles of the scap-ula when compared with position players. All players (ex-cept infielders) exhibited significantly stronger depressormuscles of the scapula on the throwing side comparedwith the nonthrowing side. In addition, we believe thatthe agonist/antagonist muscle ratios are important valueswhen considering how the scapula provides stability, mo-bility, and symptom-free function. Table 2 illustrates thescapular muscle strength values in the overhead throwingathlete.

Proprioception

Proprioception is defined as the conscious or unconsciousawareness of joint position, whereas neuromuscular con-

TABLE 1Glenohumeral Muscular Strength Values (in percent) in

Professional Baseball Playersa

180 deg/s 300 deg/s 450 deg/s

Bilateral comparisonsExternal rotation 95–109 85–95 80–80Internal rotation 105–120 100–115 100–110Abduction 100–110 100–110Adduction 120–135 115–130

Unilateral muscle ratiosExternal/internal

rotation63–70 65–72 62–70

Abduction/adduction 82–87 92–97External

rotation/abduction64–69 66–71

Isokinetic torque/bodyweight ratios

External rotation 18–23 15–20Internal rotation 27–33 25–30Abduction 26–32 20–26Adduction 32–36 28–33

a Data condensed from Wilk et al.94,96

TABLE 2Scapular Muscle Values and Their Unilateral Ratiosa

Scapular muscle values (in foot-pounds)

Protraction Retraction Elevation Depression

D ND D ND D ND D ND

Pitchers 71 � 10 74 � 13 62 � 8 60 � 7 83 � 14 84 � 5 22 � 6 18 � 5Catchers 68 � 10 73 � 10 63 � 5 59 � 7 88 � 15 85 � 8 21 � 4 16 � 5Position players 58 � 10 58 � 11 57 � 6 56 � 6 65 � 12 66 � 11 19 � 5 18 � 5

Unilateral muscle ratios (in percent)

Protraction/Retraction Elevation/Depression

D ND D ND

Pitchers 87 81 27 21Catchers 93 81 24 19Position players 98 94 29 27

a D, dominant; ND, nondominant.

138 Wilk et al. American Journal of Sports Medicine

trol is the efferent motor response to afferent (sensory)information.53 The thrower relies on enhanced propriocep-tion to influence the neuromuscular system to dynami-cally stabilize the glenohumeral joint in the presence ofsignificant capsular laxity and excessive range of motion.Allegrucci et al.2 tested the shoulder proprioception in 20healthy overhead throwing athletes participating in vari-ous sports. Testing of joint proprioception was performedon a motorized system with the subject attempting toreproduce a specific joint angle. The investigators notedthat the dominant shoulder exhibited diminished propri-oception compared with the nondominant shoulder. Theinvestigators also noted improved proprioception near theend range of motion when compared with the startingpoint.

Blasier et al.12 reported that, in persons with clinicallydetermined generalized joint laxity, the laxity is signifi-cantly less sensitive during proprioceptive testing. Wilk etal. (unpublished data, 2000) studied the proprioceptivecapability of 120 professional baseball players. The inves-tigators passively positioned the player’s arm at a docu-mented point within the player’s external rotation rangeof motion. The athlete was then instructed to activelyreposition the shoulder in the same position. The re-searchers noted no significant difference between thethrowing shoulder and nonthrowing shoulder. In addition,Wilk et al. (unpublished data, 2000) compared the propri-oceptive ability of 60 professional baseball players withthat of 60 nonoverhead throwing athletes. The investiga-tors noted no significant differences between baseballplayers and the others. However, baseball players exhib-ited slightly improved proprioceptive abilities at externalrotation end range of motion compared with nonoverheadathletes, but these results were not significantly different.

THE REHABILITATION PROGRAM FOR THEOVERHEAD THROWER

The nonoperative rehabilitation program used for treat-ment of shoulder injuries to the overhead thrower involvesa multiphased approach that is progressive and sequen-tial. The specific goals of each of the four phases of theprogram are outlined in Table 3. Each phase represents aprogression from the prior phase: the exercises becomemore aggressive and demanding, and the stresses appliedto the shoulder joint gradually increase. We will brieflydiscuss the specific rehabilitation exercises and drills thatwe use to treat the overhead throwing athlete.

There are 10 rehabilitation principles that we followwhen treating a throwing athlete. These principles areshown in Table 4.

Phase One—Acute Phase

The primary goals of the initial rehabilitation phase are toimprove flexibility, reestablish baseline dynamic stability,normalize muscle balance, and restore proprioceptionwithout causing shoulder irritation or pain. One of thegoals—to diminish the athlete’s pain and inflamma-tion—is accomplished through the use of local therapeutic

modalities such as ice, ultrasound, and electrical stimula-tion. In addition, the athlete’s activities (such as throwingand exercises) must be modified to a pain-free level. Thethrower is often instructed to abstain from throwing untiladvised by the physician or rehabilitation specialist. Ad-ditionally, active-assisted motion exercises have beenshown to assist in reducing the athlete’s pain.69

Another essential goal during the first phase of rehabil-

TABLE 3Rehabilitation of the Overhead Thrower—Phases and Goals

Phase one—acute phaseGoals

Diminish pain and inflammationNormalize motionRetard muscular atrophyReestablish dynamic stability (muscular balance)Control functional stress/strain

Exercises and modalities:Cryotherapy, ultrasound, electrical stimulationFlexibility and stretching for posterior shoulder muscles

(improve internal rotation and horizontal adduction)Rotator cuff strengthening (especially external rotator

muscles)Scapular muscles strengthening (especially retractor,

protractor, depressor muscles)Dynamic stabilization exercises (rhythmic stabilization)Closed kinetic chain exercisesProprioception trainingAbstain from throwing

Phase two—intermediate phaseGoals

Progress strengthening exerciseRestore muscular balance (external/internal rotation)Enhance dynamic stabilityControl flexibility and stretches

Exercises and modalitiesContinue stretching and flexibility (especially internal

rotation and horizontal adduction)Progress isotonic strengthening● Complete shoulder program● Thrower’s Ten programRhythmic stabilization drillsInitiate core strengthening programInitiate leg program

Phase three—advanced strengthening phaseGoals

Aggressive strengtheningProgress neuromuscular controlImprove strength, power, and enduranceInitiate light throwing activities

Exercises and modalitiesFlexibility and stretchingRhythmic stabilization drillsThrower’s Ten programInitiate plyometric programInitiate endurance drillsInitiate short-distance throwing program

Phase four—return-to-activity phaseGoals

Progress to throwing programReturn to competitive throwingContinue strengthening and flexibility drills

ExercisesStretching and flexibility drillsThrower’s Ten programPlyometric programProgress interval throwing program to competitive

throwing


itation is to normalize shoulder motion, particularlyshoulder internal rotation and horizontal adduction. It iscommon for the overhead thrower to exhibit a significantloss of internal rotation. This may be due to soft tissuetightness, which may be from muscle inflexibility due tosignificant and repetitive eccentric muscle forces duringarm deceleration. If the posterior soft tissue structuressuch as the infraspinatus and teres minor muscles aretight, increased anterior translation of the humeral headmay result.35 Therefore, the thrower should perform spe-cific stretches and flexibility exercises for the benefit ofthe posterior rotator cuff muscles.

We believe that the loss of internal rotation is due toosseous adaptation of the humerus and posterior muscletightness.21 We do not believe that the loss of internalrotation is routinely due to posterior capsular tightness. Itappears that most throwers exhibit significant posteriorlaxity when evaluated.21 Thus, to improve internal rota-tion motion and flexibility, we prefer the stretches illus-trated in Figures 2 and 3. These stretches are performedto maintain the flexibility of the posterior musculature,which may become tight because of the muscle contractionduring the deceleration phase of throwing. We do notrecommend performing stretches for the capsule unlessthe capsule has been shown on clinical examination to beexcessively hypomobile.

The rehabilitation specialist, in addition to helping re-store glenohumeral motion, should assess the resting po-sition and mobility of the scapula. Frequently, we haveseen overhead throwers who exhibit a posture of roundedshoulders and a forward head. This posture may lead tomuscle weakness of the scapular retractor muscles due toprolonged elongation or sustained stretches. In addition,the scapula may often appear protracted and anteriorlytilted. An anteriorly tilted scapula has been shown tocontribute to subacromial impingement.58 In overheadthrowers, we have seen this scapular position abnormalitycorrelate to pectoralis minor muscle tightness and lowertrapezius muscle weakness. Tightness of the pectoralisminor muscle can lead to axillary artery occlusion andneurovascular symptoms such as arm fatigue, pain, ten-derness, and cyanosis.6,70,75,78 The lower trapezius mus-cle is an important muscle in arm deceleration in that itcontrols scapular elevation and protraction.26 Weaknessof the lower trapezius muscle may result in impropermechanics or shoulder symptoms. Thus, the rehabilitation

specialist should carefully assess the position, mobility,and strength of the overhead thrower’s scapula. We rou-tinely have throwers stretch their pectoralis minor muscleand strengthen the lower trapezius muscle and scapularretractor and protractor muscles.

Additional primary goals of this first phase are to re-store muscle strength, reestablish baseline dynamic sta-bility, and restore proprioception. In this early phase ofrehabilitation, the goal is to reestablish muscle bal-ance.94,96 Therefore, the focus is on improving thestrength of the weak muscles such as the external rotatormuscles, the supraspinatus muscle, and the scapular mus-cles.94,96 The scapular muscles we routinely focus on inrehabilitation are the trapezius, serratus anterior, andrhomboid muscles. If the injured athlete is extremely soreor painful, submaximal isometric exercises should be em-ployed; conversely, if the athlete exhibits minimal soreness,

TABLE 4Principles of Rehabilitation in the Thrower

1. Never overstress healing tissue2. Prevent negative effects of immobilization3. Emphasize external rotation muscular strength4. Establish muscular balance5. Emphasize scapular muscle strength6. Improve posterior shoulder flexibility (internal rotation

range of motion)7. Enhance proprioception and neuromuscular control8. Establish biomechanically efficient throwing9. Gradually return to throwing activities

10. Use established criteria to progress

Figure 2. Internal rotation stretch: the arm is placed in thethrowing position and passively stretched into internal rota-tion to stretch the external rotator muscles.

Figure 3. To improve posterior shoulder flexibility, the hori-zontal adduction stretch can be performed at 90° of shoulderabduction. The arm is horizontally adducted while the scap-ula is stabilized to enhance the posterior shoulder stretch.


then lightweight isotonic exercises may be safely initiated.Additionally, during this phase we use rehabilitation exer-cise drills (see the next paragraph) that are designed torestore the neurosensory properties of the shoulder capsulethat has experienced microtrauma and to enhance the sen-sitivity of the afferent mechanoreceptors.53,55

Specific drills that restore neuromuscular control dur-ing this initial phase are rhythmic stabilization and recip-rocal isometric muscle contractions for the internal/exter-nal rotator muscles of the shoulders. Additionally,proprioceptive neuromuscular facilitation patterns areused with rhythmic stabilization and slow reversal hold toreestablish proprioception and dynamic stabiliza-tion.51,53,55,79,93,96 The purpose of these exercise drills isto facilitate agonist/antagonist muscle cocontractions. Ef-ficient coactivation assists in restoring the balance in theforce couples of the shoulder joint, thus enhancing jointcongruency and joint compression.37 Padua et al.71 usedproprioceptive neuromuscular facilitation patterns for 5weeks and significantly improved their subjects’ shoulderfunction and enhanced functional throwing performancetest scores. Uhl et al.83 reported improved proprioceptionafter specific neuromuscular training that challenged theglenohumeral musculature.

Other exercise drills commonly used during this firstrehabilitation phase include joint repositioningtasks52,53,54 and axial loading exercises (such as closedkinetic chain). Active joint compression stimulates thearticular receptors.19,52 Thus, axial loading exercise drillssuch as weight shifts, weight shifting on a ball, wall push-ups, and quadruped positioning drills are beneficial inrestoring proprioception.90,92,95

Phase Two—Intermediate Phase

In phase two of the rehabilitation program, the primarygoals are to progress the strengthening program, continueto improve flexibility, and facilitate neuromuscular con-trol. During this phase, the rehabilitation program is pro-gressed to more aggressive isotonic strengthening activi-ties with emphasis on the restoration of muscle balance.Selective muscle activation is also used to restore musclebalance and symmetry. In the overhead thrower, theshoulder external rotator muscles, scapular retractormuscles, and protractor and depressor muscles are fre-quently isolated because of weakness. We have estab-lished a core exercise program for the overhead throwerthat specifically addresses the vital muscles involved inthe throwing motion.90,98 This exercise program was de-veloped on the basis of the collective EMG research ofnumerous investigators,11,24,30,38,45,46,56,65,66,73,81 andis referred to as the “Thrower’s Ten Program�.”90 Sidely-ing external rotation (Fig. 4) and prone rowing into exter-nal rotation (Fig. 5) have been shown to elicit the highestamount of EMG activity of the posterior rotator cuffmuscles.30

The scapula provides proximal stability to the shoulderjoint, enabling distal segment mobility. Scapular stabilityis vital for normal asymptomatic arm function. Severalauthors have emphasized the importance of scapular mus-cle strength and neuromuscular control in contributing tonormal shoulder function.23,48,49,72 Isotonic exercise tech-niques are used to strengthen the scapular muscles. Fur-thermore, Wilk and Arrigo93 developed specific exercisedrills to enhance neuromuscular control of the scapulotho-racic joint. These exercise drills are designed to maximallychallenge the scapulothoracic muscle force couples and tostimulate the proprioceptive and kinesthetic awareness ofthe scapula. These scapular neuromuscular control drillsare illustrated in Figure 6.

Another popular exercise used by athletes is the “emptycan” exercise (Fig. 7). With this exercise movement, thearm is placed in the scapular plane with the hand placed

� To request a copy of this four-page illustrated program, please write to thecorresponding author.

Figure 4. External rotation with a dumbbell, with the patientlying on his side, is one of the exercises to increase externalrotation strength.

Figure 5. Prone rowing into external rotation is anotherexercise to enhance external rotation strength.


in full internal rotation (thumb down).44 Originally, Jobeand Moynes44 reported high levels of EMG activity in thesupraspinatus muscle during this exercise. Recently, sev-eral investigators have tested the efficiency of this exer-cise. Townsend et al.81 reported that the best exercise toactivate the supraspinatus muscle was the military shoul-der press, but this exercise is not recommended for theoverhead throwing athlete. Furthermore, the investiga-tors noted that the empty can exercise produced highEMG activity but only when the arm was elevated from

90° to 120°, which places the upper extremity into animpingement type of position.81 Blackburn et al.11 notedthat the position with the patient lying prone and with thearm abducted to 100° and full external rotation (Fig. 8)produced the highest EMG activity in the supraspinatusmuscle, compared with the empty can position. Thisexercise maneuver, advocated by Blackburn et al.,11 hasbeen substantiated by Malanga et al.61

Many times when athletes perform the empty can exer-cise they complain of shoulder pain during this maneuver.We believe the shoulder pain may be occurring because ofsuperior displacement of the humeral head due to weak-ness of the external rotator muscles. Overhead throwingathletes often exhibit external rotator muscle weakness;thus, we advocate the “full can” exercise (Fig. 9) instead ofthe empty can exercise in an attempt to avoid the possi-bility of causing superior humeral head displacement,which may lead to pain and inflammation.

Also during this second rehabilitation phase, the over-head throwing athlete is instructed to perform core

Figure 6. Neuromuscular control exercise drill for the scap-ular muscles: the athlete lies on his side with the hand placedon the table (A) and the clinician applies manual resistance toresist scapular movements (such as protraction and retrac-tion) (B). The athlete is instructed to perform slow and con-trolled movements.

Figure 7. The empty can exercise movement. This exercisecan produce pain in some athletes. For this exercise, thesubject elevates the arm in the plane of the scapula with thethumb pointed downward. The hand position appears toresemble that of emptying a can, hence comes the name ofthe exercise.


strengthening exercises for the abdomen and lower backmusculature. Plus, the athlete should perform lower ex-tremity strengthening and participate in a running pro-gram, including jogging and sprint timing. Upper extrem-ity stretching exercises are continued as needed tomaintain soft tissue flexibility.

Phase Three—Advanced Strengthening Phase

In phase three, the advanced strengthening phase, thegoals are to initiate aggressive strengthening drills, en-hance power and endurance, perform functional drills,and gradually initiate throwing activities. During thisphase, the athlete performs the Thrower’s Ten exerciseprogram, continues manual resistance stabilization drills,and initiates plyometric drills. Dynamic stabilizationdrills are also performed to enhance proprioception andneuromuscular control. These drills include rhythmic sta-bilization exercise drills by throwing a ball into a wall(Fig. 10), push-ups onto a ball (Fig. 11), and ball throws.Plyometric training (described in the next paragraph) maybe used to enhance dynamic stability, enhance propriocep-tion, and gradually increase the functional stresses placedon the shoulder joint.

Plyometric exercise employs three phases, all intendedto use the elastic and reactive properties of the muscle togenerate maximum force production.13,16,18 The firstphase is the eccentric phase, where a rapid prestretch isapplied to the musculotendinous unit, stimulating themuscle spindle. The second phase is the amortization

Figure 8. Prone horizontal abduction at 110° of shoulderabduction and full external rotation. This exercise produceshigh levels of EMG activity of the posterior rotator cuff, su-praspinatus, and lower trapezius muscles.

Figure 9. The full can exercise movement. This exercise isperformed in the plane of the scapula. The subject elevatesthe arm with the thumb pointed upward, as if not to spillcontents of an imaginary can, stopping at 90° of elevation.

Figure 10. Rhythm stabilization exercise drill: the subjectthrows a 2-pound Plyoball (Functional Integrated Technolo-gies, Watsonville, California) against the wall, at the end-range of external rotation (late cocking).


phase, representing the time between the eccentric andconcentric phases. This time should be as short as possibleso that the beneficial neurologic effects of the prestretchare not lost. The final phase is the resultant concentriccontraction. Wilk et al.88,98 established a plyometric exer-cise program for the overhead thrower. The initial plyo-metric program consists of two-handed exercise drills suchas a chest pass, overhead soccer throw, side-to-sidethrows, and side throws (Figs. 12 through 14). The goal ofthe plyometric drills is the transfer of energy from the legsand trunk to the upper extremity. Once these two-handedexercise drills are mastered, the athlete is progressed to

Figure 11. Rhythm stabilization exercise drill: the subjectperforms a push-up into a Plyoball. At midrange, the subjectholds that position.

Figure 12. A plyometric exercise drill: a two-handed chestpass using an 8-pound Plyoball that is thrown into a Plyoback(Functional Integrated Technologies).

Figure 13. A plyometric exercise drill: a two-handed over-head soccer throw.

Figure 14. A plyometric exercise drill: a two-handed sidethrow using an 8-pound Plyoball. Note the use of the lowerextremity and hips to produce trunk and shoulder rotation.-

Figure 15. A plyometric exercise drill: a one-handed base-ball throw with use of a 2-pound Plyoball.


one-handed drills. These drills include standing one-handed throws in a functional throwing position (Fig. 15),wall dribbling, and plyometric step and throws. Swanik etal.80 reported that a 6-week plyometric training programresulted in enhanced joint position sense, enhanced kin-esthesia, and decreased time to peak torque generationduring isokinetic testing. Fortun et al.32 noted improvedshoulder internal rotation power and throwing distanceafter 8 weeks of plyometric training in comparison withconventional isotonic training.

Additionally, muscle endurance exercises should be em-phasized for the overhead thrower. Recently, Murray etal.67 documented the effects of fatigue on the entire bodyduring pitching using kinematic and kinetic motion anal-ysis. Once the thrower was fatigued, shoulder externalrotation decreased and ball velocity diminished, as didlead knee flexion and shoulder adduction torque. Voight etal.86 documented a relationship between muscle fatigueand diminished proprioception. Chen et al.17 demon-strated that once the rotator cuff muscles are fatigued, thehumeral head migrates superiorly when arm elevation isinitiated. Recently, Gladstone et al. (unpublished data,1996) documented that once the shoulder musculaturefatigues in professional baseball pitchers during gamesituations, the humeral head translates superiorly. Fur-thermore, Lyman et al.59 reported that the predisposingfactor that correlated to the highest percentage of shoul-der injuries in Little League pitchers was complaints ofmuscle fatigue while pitching. Thus, the endurance exer-cise drills described here appear critical for the overheadthrower.

Specific endurance exercise drills we use include walldribbling with a Plyoball (Functional Integrated Technol-ogies, Watsonville, California), wall arm circles, upperbody cycle, or isotonic exercises using lower weights withhigher repetition. Other techniques that may be beneficialto enhance endurance include throwing an under-weighted or overweighted ball (that is, a ball that iseither less than or more than the weight of an officialbaseball).14, 18, 25, 27, 57, 84 These techniques are designedto enhance training, coordination, and the transfer of ki-netic energy. Fortun et al.32 noted an increase in internalrotation strength and power after an 8-week plyometrictraining program using a weighted ball. Most commonly,the underweighted ball is used to improve the transfer ofenergy and angular momentum.25,27,84 Conversely, theoverweighted ball is generally used to enhance shoulderstrength and power.25,27,84

Also, during this third rehabilitation phase an intervalthrowing program may be initiated. Before initiating sucha program, we occasionally suggest that the athlete per-form “shadow” throwing or mirror throwing, which is theaction of mimicking the throwing mechanics into a mirror,but not actively throwing. This is designed to allow theathlete to work on proper throwing mechanics beforethrowing a baseball. The interval throwing program isinitiated once the athlete can fulfill these specific criteria:1) satisfactory clinical examination, 2) nonpainful range ofmotion, 3) satisfactory isokinetic test results, and 4) ap-propriate rehabilitation progress. The interval throwing

program is designed to gradually increase the quantity,distance, intensity, and type of throws needed to facilitatethe gradual restoration of normal biomechanics.

Interval throwing is organized into two phases: phase Iis a long-toss program (from 45 to 180 feet) and phase II isan off-the-mound program for pitchersa.90 During thisthird rehabilitation phase, we usually initiate phase I ofthe interval throwing program at 45 feet and progress tothrowing from 60 feet. The athlete is instructed to use acrow-hop type of throwing mechanism and lob the ballwith an arc for the prescribed distance. Flat ground, long-toss throwing is used before throwing off the mound toallow the athlete to gradually increase the applied loads tothe shoulder while using proper throwing mechanics. Inaddition, during this phase of rehabilitation, we routinelyallow the position player to initiate a progressive battingprogram. We routinely use a program that progresses theathlete from swinging a light bat, to hitting a ball off a tee,to soft-toss hitting, to batting practice.

Phase Four—Return-to-Throwing Phase

Phase four of the rehabilitation program, the return-to-throwing phase, usually involves the progression of theinterval throwing program. For pitchers, we progress thelong-toss program to 120 or 145 feet, whereas positionplayers would progress to throwing from 180 feet. Oncethe pitcher has successfully completed throwing from 120or 145 feet, the athlete is instructed to throw 60 feet fromthe windup on level ground. Once this step is successfullycompleted, phase II, throwing from the mound, is per-formed. Position players continue to progress the long-tossprogram to 180 feet, then perform fielding drills from theirspecific position. While the athlete is performing the in-terval throwing program, the clinician should carefullymonitor the thrower’s mechanics and throwing intensity.In a study conducted at our biomechanics laboratory, weobjectively measured the throwing intensity of healthypitchers. When pitchers were asked to throw at 50% effort,radar gun analysis indicated that the actual effort wasapproximately 83% of their maximum speed. When askedto throw at 75% effort, the pitchers threw at 90% of theirmaximum effort.31 This indicates that these athletesthrew at greater intensities than were suggested, whichmay imply difficulty of controlling velocity at lower throw-ing intensities.

In addition, during this fourth phase the thrower isinstructed to continue all the exercises previously pre-scribed to improve upper extremity strength, power, andendurance. The athlete is also instructed to continue thestretching program, core exercise training, and lower ex-tremity strengthening activities. Lastly, the athlete iscounseled on a year-round conditioning program based onthe principles of periodization.85 Thus, the athlete is in-structed when to begin such things as strength trainingand throwing.96 To prevent the effects of overtraining or

a To request copies of the phases of the interval throwing program, pleasewrite to the corresponding author.


throwing when poorly conditioned, it is critical to instructthe athlete specifically on what to do through specificexercises throughout the year (Fig. 16). This is especiallycritical in preparing the athlete for the following season.Wooden et al.99 demonstrated that performing a dynamicvariable resistance exercise program significantly in-creases throwing velocity.

SPECIFIC REHABILITATION GUIDELINES

To successfully rehabilitate the overhead thrower, an ac-curate differential diagnosis is imperative. Once the diag-nosis is established, an appropriate rehabilitation pro-gram can be formulated. Often, the previously mentionedprogram must be modified based on the specific disorderexhibited by the thrower. In this section, we will discussthe rehabilitation guidelines for several common injuriesthat occur in the overhead thrower.

Posterosuperior Glenoid Impingement

Posterosuperior glenoid impingement, often referred to asinternal impingement, is one of the most frequently ob-served injuries to the overhead throwing athlete (Refs.3–5, 40–42, 62, 87; J. R. Andrews, unpublished data,1996). We believe that one of the underlying causes ofsymptomatic internal impingement is excessive anteriorshoulder laxity. One of the primary goals of the rehabili-tation program is to enhance the athlete’s dynamic stabi-lization abilities, thus controlling anterior humeral headtranslation. Another essential goal is to restore flexibilityto the posterior rotator cuff muscles of the glenohumeraljoint. We strongly suggest caution against aggressivestretching of the anterior and inferior glenohumeral struc-tures as this may result in increased anterior translation.Additionally, the program emphasizes muscle strengthen-

ing of the posterior rotator cuff to reestablish muscle bal-ance and improve joint compression abilities.

The scapular muscle must be an area of increased focusas well. Restoring dynamic stabilization is an essentialgoal to minimize the anterior translation of the humeralhead during the late cocking and early acceleration phasesof throwing. Exercise drills such as proprioceptive neuro-muscular facilitation patterns with rhythmic stabilizationare incorporated.92,94 Also, stabilization drills performedat end-range external rotation are beneficial in enhancingdynamic stabilization (Fig. 17). Perturbation training ofthe shoulder joint is performed to enhance proprioception,dynamic stabilization, and neuromuscular control. We be-lieve that this form of training has been extremely effec-tive in treating the thrower who has posterior/superiorimpingement.

Once we have restored posterior flexibility, normalizedglenohumeral strength ratios, enhanced scapular musclestrength, and diminished the patient’s symptoms, an in-terval throwing program may be initiated. Jobe40 sug-gested abstaining from throwing for 2 to 12 weeks beforethe throwing program, depending on the thrower’s symp-toms. Once the thrower begins the interval throwing pro-gram, the clinician or pitching coach should observe thethrowing mechanics frequently. Occasionally, throwerswho exhibit internal impingement will allow their arm tolag behind the scapula, thus throwing with excessive hor-izontal abduction and not throwing with the humerus inthe plane of the scapula (Fig. 18). Jobe and col-leagues40,43,46 referred to this as “hyperangulation” of thearm. This type of fault leads to excessive strain on theanterior capsule and to internal impingement of the pos-terior rotator cuff.40–42 Correction of throwing pathome-chanics is critical to returning the athlete to asymptom-atic and effective throwing.

Figure 16. The concept of periodization for the overheadthrowing athlete. The graph illustrates that volume, intensity,and technique should be adjusted based on the time of theyear (that is, preseason, in-season, and postseason). (FromWilk et al.90)

Figure 17. Rhythmic stabilization drills to enhance dynamicglenohumeral joint stability. The athlete is instructed to max-imally externally rotate, then perform reciprocal isometriccontractions to enhance dynamic joint stability. The goal ofthis exercise is to maintain a specific joint angle.


Overuse Syndrome Tendinitis

Occasionally, throwers will describe the symptoms andexhibit the signs of overuse tendinitis of the shouldermusculature. The tendinitis signs and symptoms can be ofthe rotator cuff or of the long head of the biceps brachiimuscles, or both. These signs frequently occur early in theseason, when the athlete’s arm is not in the best condition.They can also occur at the end of the competitive seasonwhen the athlete begins to fatigue. Additionally, we seethese signs develop when the athlete does not perform thein-season strengthening program while throwing. Mereparticipation in throwing activities does not ensure themaintenance of proper shoulder muscle strength and flex-ibility. Specific muscles (external rotator muscles, scapu-lar muscles) often become weak and painful because of thestresses involved with throwing.

The rehabilitation program for overuse rotator cuffmuscle tendinitis should concentrate on treating thecause(s) of the tendinitis and not merely the symptoms.The athlete is often instructed to discontinue throwing fora short period (2 to 4 weeks) to reduce inflammation andrestore strength and flexibility. Other times, the athlete isinstructed to reduce the number of throws during compe-tition or practice. Thus, a strict pitch count is enforced.The rehabilitation program will be successful if the causeis identified, throwing activities are modified, and properstrength and flexibility are restored.

Often, the thrower will complain of bicipital pain, occa-sionally referred to as “groove pain.” The biceps brachiimuscle appears to be moderately active during the over-head throwing motion. DiGiovine et al.26 reported peak

EMG activity of 44% � 32% maximum voluntary isomet-ric contraction during the deceleration phase of throwing.In our opinion, bicipital tendinitis that is present in theoverhead thrower usually represents a secondary condi-tion. The primary disorder may be instability, a SLAP(superior labral, anterior and posterior) lesion, or somesimilar malady. The rehabilitation of this condition fo-cuses on improving dynamic stabilization of the glenohu-meral joint through muscle training drills. Knatt et al.50

studied the synergistic action of the capsule and shouldermuscles in a feline model and described a glenohumeraljoint capsule-biceps reflex. The authors reported thatstimulation of the anterior capsule caused a reflexive bi-ceps muscle contraction. They demonstrated that the bi-ceps brachii muscle was the first muscle to reflexivelyrespond to stimulation of the capsule, occurring in 2.7msec. Therefore, it is the belief of one of the authors(KEW) that the biceps brachii muscle is activated to agreater extent when the thrower exhibits hyperlaxity orinflammation of the capsule.

Glousman et al.33 reported that throwers with instabil-ity exhibited a higher level of rotator cuff EMG activitycompared with throwers without instability. Further-more, Gowan et al.34 noted higher EMG activity in ama-teur throwers compared with skilled throwers. Nonopera-tive rehabilitation for this condition usually consists of areduction in throwing activities and reestablishment ofdynamic stability and modalities such as ice, ultrasound,iontophorosis, and electrical stimulation to reduce bicipi-tal inflammation.

Posterior Rotator Cuff Musculature Tendinitis

The successful treatment of posterior rotator cuff muscu-lature tendinitis, or tensile rotator cuff musculature fail-ure, depends on its differential diagnosis from internalimpingement. Frequently, the athlete complains of pain inthe same location for both lesions. However, subjectivelythe athlete notes posterior shoulder pain during the de-celeration phase of throwing. Conversely, athletes whoexhibit internal impingement complain of pain during thelate cocking and early acceleration phases. During thedeceleration phase of the overhead pitch, the distractionforces at the glenohumeral joint approach one to one anda half times body weight.29 These are excessive forces thatmust be dissipated and opposed by the posterior rotatorcuff muscles. Pitchers occasionally exhibit this condition.Once the athlete is examined, the most common findingsare significant posterior rotator cuff muscle weakness,weakness of the lower trapezius muscle and scapular re-tractor muscles, and tightness of the posterior rotator cuffmuscles.

The rehabilitation program focuses on several key ar-eas. First, throwing activities are discontinued until theathlete exhibits proper muscle strength ratios betweenthe external and internal rotator muscles. This ratioshould be at least 64% (optimal goal, 66% to 75%).94 Sec-ond, the athlete is placed on an aggressive strengtheningprogram for the posterior rotator cuff muscles and theretractor and depressor muscles of the scapula. Exercises

Figure 18. Hyperangulation during the overhead throwingmotion. During the late cocking phase of the overhead throw,as the thrower’s humerus excessively abducts horizontally,posterosuperior impingement of the shoulder joint may oc-cur. To prevent this, the thrower must stay in the plane of thescapula. A, normal angular relationship; B, hyperangulation.(Reprinted with permission from Davidson PA, ElattracheNS, Jobe CM, et al: Rotator cuff and posterior-superior gle-noid injury associated with increased glenohumeral motion:A new site of impingement. J Shoulder Elbow Surg 4: 384–390, 1995.)


that we emphasize are sidelying external rotation, pronerowing into external rotation, prone horizontal abductionwith external rotation, scapular retraction, and prone hor-izontal abduction. Fleisig et al.30 have shown that teresminor muscle EMG activity can be enhanced with the useof a towel roll placed between the humerus and the side ofthe body. Once strength levels have improved, the exerciseprogram should emphasize eccentric muscle training. Inparticular, the external rotator muscles and the lowertrapezius muscle are the focus of the eccentric program(Fig. 8). DiGiovine et al.26 determined that the EMG ac-tivity of the teres minor muscle is 84% and that of thelower trapezius muscle is 78% of a maximum voluntaryisometric contraction during the deceleration phase of thethrow. These two muscles are the most active during thisphase and, thus, must be the focus of the strengtheningprogram.

In addition, flexibility and stretching exercises for theposterior rotator cuff muscles are performed throughoutthe rehabilitation program. We also use heat and ultra-sound before stretching to enhance tissue extensibilitywhile increasing circulation to the area. Once flexibilityand muscle strength are improved and the athlete’spain and inflammation have abated, an interval throw-ing program can be initiated. The interval throwingprogram should be progressed slowly so that thestresses of throwing are gradually increased. The ath-lete is instructed to be sure to follow through properlyand not to terminate the deceleration phase abruptly,which may lead to increased stresses on the posteriorrotator cuff muscles.

SLAP Lesions

The nonoperative treatment of SLAP lesions depends onthe type of lesion present. Using the classification systemdeveloped by Snyder et al.,76 type I SLAP lesions appearas fraying of the labrum and often respond favorably to anonoperative treatment regimen. Throwers who exhibitthis type of lesion are treated with a program similar tothe posterosuperior glenoid impingement protocol (previ-ously discussed). Conversely, players with a type II or typeIV SLAP lesion are probably best served by undergoingsurgical intervention. If rehabilitation is indicated beforesurgery, the program should emphasize restoration ofrange of motion through stretching exercises within thepatient’s tolerance. Avoidance of overhead motions withexcessive internal/external rotation is enforced because ofpossible joint snapping and pain.

A strengthening program should be performed in anattempt to prevent muscle atrophy. The strengtheningexercises should be performed with the arm below shoul-der level to prevent further damage to the glenoid labrum.Strengthening exercises such as external/internal rotationwith the arm at the side or scapular plane, scapularstrengthening, and deltoid muscle exercises to 90° of ab-duction can be safely performed. Exercises such as shoul-der press, bench press, and latissimus dorsi muscle pull-downs (behind the neck) are avoided because of increasedstress applied to the superior labrum and anterior gleno-

humeral joint capsule. Furthermore, the clinician shouldbe cautious with closed kinetic chain exercises that resultin excessively high joint compressive loads that could re-sult in further compromise of the glenoid labrum.

Subacromial Impingement

Primary subacromial impingement in the young profes-sional baseball player is unusual, but it may occur.46

Subacromial impingement complaints in this group of ath-letes usually represent primary hyperlaxity leading tosecondary impingement.46 Neer and Walsh68 and Biglianiet al.9 reported that abnormal acromial architecture maylead to rotator cuff muscle disease. In cases of abnormalacromial architecture, the athlete may require surgicaltreatment. Hawkins and Kennedy36 and Penny andWelsh74 stated that the coracoacromial ligament can be aprimary source of abnormality in the athlete.

The nonoperative treatment for subacromial impinge-ment should focus on a five-step program. First, abstainfrom irritating activities such as throwing or other over-head motions for 7 to 10 days, until inflammation is di-minished. Second, normalize glenohumeral motion andcapsular mobility. Harryman et al.35 reported that poste-rior capsular tightness results in anterosuperior migra-tion of the humeral head, thus leading to subacromialimpingement. We have noted that patients with inferiorcapsular tightness frequently complain of subacromialpain. Thus, the rehabilitation program must focus on re-storing normal capsular and soft tissue mobility posteri-orly and inferiorly. The third step is to enhance dynamicstability of the glenohumeral and scapulothoracic joint.Jobe et al.46 noted subacromial impingement may be sec-ondary to hyperelasticity of the capsular ligaments. Thus,the rehabilitation program must focus on rotator cuff mus-cle strength to adequately compress and stabilize the hu-meral head within the glenoid fossa. Furthermore, scap-ular strengthening should also be an area of focus. Duringarm elevation, the scapula upwardly rotates, retracts, andposteriorly tilts. Lukasiewicz et al.58 reported that pa-tients with impingement exhibit less posterior tilting thando subjects without impingement. We have clinicallynoted this phenomenon for some time. Thus, the rehabil-itation program should include pectoralis minor musclestretching and inferior trapezius muscle strengthening toensure posterior scapular tilting. This is especially truewith the recreational baseball player who performs a sed-entary job. The fourth step is to emphasize the retractormuscles of the scapula and to correct any forward-headposture. Solem-Bertoft et al.,77 using MRI, have demon-strated that excessive scapular protraction reduces ante-rior tilt of the scapula and diminishes the acromial-hu-meral space, whereas scapular retraction increases thesubacromial space. Thus, we employ scapular retraction-strengthening exercises. The last step is a gradual returnto throwing activities once pain has significantlydiminished.


Bennett’s Lesion

The successful nonoperative treatment of throwing ath-letes with ossification of the posterior capsule (Bennett’slesion) is often difficult. It has been our clinical experiencethat the thrower with symptomatic thrower’s exostosiscan be conservatively managed for some time; however,long-term success is limited and often surgical debride-ment of the ossification may become necessary. Nonopera-tive treatment includes abstaining from throwing untilpain subsides, restoring posterior capsule and muscle flex-ibility, improving posterior rotator cuff musculature andscapular strength, and a gradual return to throwingactivities.

Primary Instability

Most skillful throwers exhibit significant hyperelasticityof their anterior glenohumeral joint capsule, which allowsexcessive external rotation and proper throwing mechan-ics. Because of the repetitive microtraumatic forces ofthrowing, the hyperelasticity may progress to primaryinstability and associated lesions and complaints. This is avery common occurrence in the overhead thrower. Thenonoperative treatment for this condition has been thor-oughly discussed in the rehabilitation program in thisarticle. The key aspects are reduction of throwing activityto allow diminished inflammation, normalization of mo-tion, restoration of proper strength of glenohumeral andscapular muscles, enhancement of proprioception, and agradual return to throwing. In the majority of cases, thistreatment will be effective.

Acute Traumatic Instability

An acute traumatic dislocation to a throwing athlete’sdominant shoulder can be devastating. The injury mayinclude a Bankart lesion, rotator cuff muscle tear, labraltear, or even injury to the brachial plexus muscle. Thetreatment for a dislocation in the thrower is surgical cor-rection. Before surgery, the athlete’s shoulder should beplaced in a sling for comfort. In addition, gentle range ofmotion exercises should be performed to gradually restoremotion before surgery. A mild strengthening program forthe glenohumeral and scapular muscles should also beperformed with the goal of preventing muscle atrophy andweakness and loss of dynamic stabilization.

Improper Mechanics

Throwing with improper or faulty mechanics can lead toshoulder pain or injury, or both, because of the abnormalstresses that are applied across various tissues. To deter-mine whether the thrower exhibits improper throwingmechanics, the clinician should carefully observe the ath-lete throw. Obvious flaws can be seen occasionally. Theclinician may often require assistance from an experi-enced and knowledgeable baseball coach. The skilled eyeof an experienced coach can frequently determine subtleabnormalities in the throwing mechanics. Perhaps the

most objective analysis is a high-speed video biomechani-cal evaluation. This can be done at a biomechanics labo-ratory using specialized high-speed video cameras andcomputer analysis of the data.

When evaluating an athlete’s throwing mechanics, wecommonly look at several different aspects of the move-ment. The clinician can use a video recorder to film thethrower and analyze the biomechanics during slow-motionplayback to pinpoint improper mechanics. Filming shouldbe performed from multiple views to accurately assess theathlete, including lateral (facing the athlete), posterior,and anterior views. We normally analyze several aspectsof the throwing motion in sequential order to detect subtlepathomechanical deviations through the phases ofthrowing.

Biomechanical analysis of the throwing motion beginswith the lateral view; there are several critical moments toobserve from this view. During the wind-up phase, thepitcher should be in a balanced position when the lead legreaches the highest point. Forward movement should notbegin until the lead leg is fully raised. Rushing the deliv-ery by falling toward home plate during the wind-upphase may decrease the amount of energy generated bythe lower body and result in a loss of velocity. As theathlete begins the early cocking phase, the path of motionas the thrower removes the ball from the glove should besmooth, with the elbow flexed and the fingers on top of theball. As the lead leg comes in contact with the ground, theknee should be slightly flexed and the elbow should belevel with the shoulder. A right-handed pitcher will showthe ball to the shortstop and a left-handed pitcher willshow the ball to the second baseman. The stride should belong enough to allow sufficient rotation and force genera-tion from the hips and trunk, approximately equal to theheight of the thrower. At maximal external rotation dur-ing the late cocking phase, the arm should be abductedapproximately 90° to 100°. Fleisig28 reported that throw-ing with reduced external rotation at the time of footcontact causes an increase in strain on the shoulder dur-ing acceleration and ball release. Furthermore, thethrower should begin straightening the elbow beforeshoulder internal rotation during the acceleration phase.At this time, the lead leg extends, or straightens, to sta-bilize the body and provide a fulcrum for body rotation.

During the deceleration and follow-through phases, thethrowing shoulder should internally rotate and horizon-tally adduct across the body. The upper extremity shouldcross the front of the body and end outside the lead leg.Abbreviating the follow-through and ending with thehand toward the target may increase the stresses appliedto the shoulder.

Observing the thrower from a posterior view allows theclinician to observe two instants during the throwing mo-tion. As the thrower removes the ball from the glove dur-ing early cocking, the arm path should move smoothly ina down, back, and upward motion as the thrower stridestoward the target. A thrower whose arm moves behind thebody may cause excessive anterior capsular straining andpossible internal impingement. Also of interest from theposterior view is the hand position during late cocking. As


previously stated, the ball should be facing the shortstopfor right-handed throwers and the second baseman forleft-handed throwers.

An anterior view of the throwing motion is helpful to theclinician to determine the position of the stride leg as thefoot comes into contact with the ground. At this time, thelead foot should be pointed toward the target. Often youngand inexperienced throwers overrotate and place the leadfoot on the first base side of the mound. This results in thepitcher’s “opening up too soon” and causes the hips torotate early, resulting in loss of velocity and increasedstrain to the anterior shoulder. Fleisig28 has shown thatas the lead foot angle becomes more open, the throwertends to throw across the body and increases the loadsapplied to the shoulder. Furthermore, “leading with theelbow” (increased horizontal adduction and elbow flexion)during the acceleration phase correlated to decreasedloads at the shoulder but increased loads on the medialaspect of the elbow.28

The orientation of the shoulder at the moment of ballrelease can also be assessed from the anterior view of thethrowing motion. The throwing elbow should be in linewith the shoulder with minimal flexion of the elbow. Thenonthrowing elbow should be tucked at the side. As theathlete progresses into the deceleration and follow-through phases, the throwing arm should follow a long arcof deceleration, allowing proper dissipation of forces fromthe arm to the trunk and lower extremities.

SUMMARY

Overhead throwing athletes typically have a unique mus-culoskeletal profile. The overhead thrower frequently ex-periences shoulder pain because of anterior capsular lax-ity and increased demands placed on the dynamicstabilizers. This may be the result of repetitive highstresses imparted to the shoulder joint and may lead tothe development of injuries. Most commonly, these inju-ries are overuse injuries and can be successfully managedwith a well-structured rehabilitation program. The reha-bilitation program should focus on the correction of adap-tive changes seen in the overhead thrower, such as loss ofinternal rotation and muscle weakness of the externalrotator muscles and scapular muscles. The rehabilitationspecialist may then initiate the athlete’s gradual throwingprogram to return to competition. The athlete’s overheadthrowing motion should be examined to determinewhether improper biomechanics are contributing to theinjury. Lastly, education of the athlete in the area ofyear-round conditioning is imperative. The overheadthrowing athlete should be instructed as to when to beginconditioning and throwing to prepare for the next compet-itive season and prevent subsequent injury.

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